The increase in demand for longer-lasting battery-powered devices such as portable electronics and electric vehicles creates a need for energy storage technologies that provide higher energy and power densities. The relatively sluggish progress of lithium-ion batteries, first commercialized by Sony in 1991, demonstrates the need for new electrode materials that meet consumer demands and expectations. In the last few decades, intercalation materials containing phosphate groups (PO4) have garnered interest due to several intrinsic advantages. The robust structure of the PO4 group provides an open 3D network allowing for long term cycling and high ionic diffusion rates. The inherent stability of the PO4 group derives from the tetrahedral coordination of the phosphorous-oxygen covalent bonds, which engender several desirable properties including resistance to thermal degradation and overcharge. The most well-known phosphate, the triphylite LiFePO4, was first introduced in 1997. This phospholivine of type LiMPO4 (M=Co, Cu, Fe, Mn, Ni) is an inexpensive, environmentally friendly, but low energy cathode material that requires various conductive additives to enable exceptionally high power. Subsequent to this pioneering work, there has been great interest in phosphate intercalation compounds for positive and negative electrodes in lithium batteries. Metal phosphates are also being investigated as model intercalation materials to further the understanding of the intrinsic reaction mechanisms and limitations to elucidate new pathways towards improved battery technology.